Sorry to be boring, but not many other suggestions coming through, so personally I think Voix Du Reve will be the Mullins horse in this, as I have said previously.
I know he's not quite as 'sexy' as the others mentioned but ultimately could come on a bundle for going over fences and certainly looked like he took to them as well as anything on his chase debut.
He's not devoid of some level of Chletenham form and I am happy to forgive his run at this years festival as quite frankly his whole campaign was a mess, but that previous festival form when he would have at least pushed Diego Du Charmil close if not beat him, before falling, is not form to take lightly.
He'll certainly be overpriced currently and won't be 25/1 come the day of the festival should he make it.
There is also some confidence behind the breeding side of it too to suggest chasing will be a positive step for him, the sire, Voix Du Nord, also sired Vroum Vroum Mag (unbeaten over fences), Taquin Du Seuil (won this race as a novice chaser), Vibrato Valtat (Quirky, but made a fair novice chaser, winning some weakish Grade 1 & 2 races, albeit not at the festival) & Vaniteux (another who was a fairly consistent novice chaser, winning and placing in Graded races, as well as looking like finishing 2nd to Douvan in the Arkle at the festival before falling). Unfortunately there is not a whole heap on the Dams side to be as confident about, and obviously it goes without saying that Voix Du Nord has also had his fair share of poor progeny too, however Voix Du Reve has shown better form over hurdles than the majority of them already so I have no doubt he has a little class about him and it will show through over fences.